Electric utility energy distribution systems are used to distribute electric energy from electric power generation plants to electric energy consumers. FIG. 1 is a schematic diagram of part of an example electric energy distribution system 10. A high voltage primary distribution line 12 provides electric energy to a distribution transformer 14. Distribution transformer 14 is connected to a lower voltage secondary distribution line 16, and steps down the voltage of primary line 12 to the voltage of secondary distribution line 16. Secondary distribution line 16 is connected to a plurality of branches 18A, 18B, and 18C corresponding to different energy consumers 20A, 20B and 20C. The consumption of energy by consumers 20A, 20B and 20C is metered by consumer meters 22A, 22B and 22C provided on branches 18A, 18B and 18C, respectively.
An unfortunate reality of electric utility energy distribution is that electric energy is sometimes unlawfully diverted to avoid metering. The unlawful diversion of electric energy is sometimes referred to in the electric energy industry as electricity theft or non-technical losses. Two common forms of electric energy diversion are bypasses and taps.
In FIG. 1, a bypass 24 provides an electrical path in parallel to meter 22B, such that a portion of the energy consumed by consumer 20B bypasses meter 22B so as not to be accounted for in meter 22B's measurement of electric energy consumption. Because bypass 24 is connected at either side of meter 22B, the amount of electric energy diverted through bypass 24 is related to the amount of electric energy delivered through meter 22B.
FIG. 1 also shows a distribution tap 26. Distribution tap 26 provides an additional electrical path from branch 18C to consumer 20C (e.g., to a separate panel) or to another consumer. Because distribution tap 26 is not connected on both sides of meter 22C, the amount of electric energy diverted through tap 26 is not related to the amount of electric energy delivered through meter 22C.
Because electric energy diversion is costly to electric energy utilities and may be linked to other criminal activity (e.g., clandestine marijuana grow operations), there is a need for quantifying and identifying sources of electric energy diversion. It is possible to quantify electric energy diversion within a particular part of an electric energy distribution network (referred to herein as an “inventory zone”) by comparing the energy delivered to the inventory zone with metered energy consumption removed from (i.e., consumed in) the inventory zone. In the context of the distribution system 10, the energy delivered to an inventory zone 28 may be measured by a meter 30 connected in series between distribution transformer 14 and secondary distribution line 16.
If only bypass diversions are present in an inventory zone, it is possible to identify where bypass diversions are located from the vector k of bypass diversion factors found by measuring energy consumption for the inventory zone and consumers within the inventory zone for a plurality of intervals, and solving the system of linear equations
                                          [                                                                                w                    11                                                                    …                                                                      w                                          1                      ⁢                                                                                          ⁢                      j                                                                                                                    ⋮                                                  ⋱                                                  ⋮                                                                                                  w                                          i                      ⁢                                                                                          ⁢                      1                                                                                        …                                                                      w                    ij                                                                        ]                    ⁡                      [                                                                                k                    1                                                                                                ⋮                                                                                                  k                    j                                                                        ]                          =                  [                                                                      w                                      z                    ⁢                                                                                  ⁢                    1                                                                                                      ⋮                                                                                      w                  zi                                                              ]                                    (        1        )            
where:                i is the number of intervals;        j is the number of consumers;        wij is the energy consumption measured for the ith time interval by the meter for the jth consumer, and        wzi is the energy consumption measured for the ith time interval by the distribution transformer meter for the inventory zone).                    For convenience, matrix equality (1) may be expressed as Wconsumerk=wzone where Wconsumer is a matrix of metered consumer load profile data wij for consumers in the inventory zone over a number of time intervals (i.e., Wconsumer=[wij]n×m for m consumers and n time intervals) and wzone is a vector of inventory zone load profile data (i.e. wzone=[wzi]m).                        
This technique fails if the inventory zone contains one or more tap diversions, since electric energy diverted by way of taps is reflected in inventory zone load profile wzone but is not reflected in the metered consumer load profiles Wconsumer. Currently, bypass diversions and tap diversions are identified by manually inspecting electric power distribution equipment (e.g., transformers, lines, meters, etc.). This is time-consuming and labour intensive.
The inventor has identified a need for methods and apparatus adapted to use metered electric energy consumption data to do one or more of the following:                quantify bypass diversion loads in an inventory zone that contains bypass diversions and tap diversions,        reliably identify the locations of bypass diversions in an inventory zone that contains bypass diversions and tap diversions,        quantify tap diversion loads in an inventory zone that contains bypass diversions and tap diversions, and        identify the locations of tap diversions in an electric utility power distribution system.        
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.